add api test cases for HVAR with index map (and fix)

src/hb-ot-var-hvar-table.hh

@@ -170,7 +170,7 @@ struct index_map_subset_plan_t
       last_gid = gid;
     }
 
-    map_count = last_gid + 1;
+    map_count = last_gid;
     for (gid = 0; gid < map_count; gid++)
     {
       hb_codepoint_t	old_gid;

test/api/test-subset-hvar.c

@@ -30,7 +30,68 @@
 /* Unit tests for HVAR subsetting */
 
 static void
-test_subset_HVAR_noop (void)
+test_subset_map_HVAR_noop (void)
+{
+  hb_face_t *face_abc = hb_test_open_font_file("fonts/AdobeVFPrototype.abc.otf");
+
+  hb_set_t *codepoints = hb_set_create ();
+  hb_face_t *face_abc_subset;
+  hb_set_add (codepoints, 'a');
+  hb_set_add (codepoints, 'b');
+  hb_set_add (codepoints, 'c');
+  face_abc_subset = hb_subset_test_create_subset (face_abc, hb_subset_test_create_input (codepoints));
+  hb_set_destroy (codepoints);
+
+  hb_subset_test_check (face_abc, face_abc_subset, HB_TAG ('H','V','A','R'));
+
+  hb_face_destroy (face_abc_subset);
+  hb_face_destroy (face_abc);
+}
+
+static void
+test_subset_map_HVAR (void)
+{
+  hb_face_t *face_abc = hb_test_open_font_file ("fonts/AdobeVFPrototype.abc.otf");
+  hb_face_t *face_ac = hb_test_open_font_file ("fonts/AdobeVFPrototype.ac.otf");
+
+  hb_set_t *codepoints = hb_set_create ();
+  hb_face_t *face_abc_subset;
+  hb_set_add (codepoints, 'a');
+  hb_set_add (codepoints, 'c');
+  face_abc_subset = hb_subset_test_create_subset (face_abc, hb_subset_test_create_input (codepoints));
+  hb_set_destroy (codepoints);
+
+  hb_subset_test_check (face_ac, face_abc_subset, HB_TAG ('H','V','A','R'));
+
+  hb_face_destroy (face_abc_subset);
+  hb_face_destroy (face_abc);
+  hb_face_destroy (face_ac);
+}
+
+static void
+test_subset_map_HVAR_retaingids (void)
+{
+  hb_face_t *face_abc = hb_test_open_font_file ("fonts/AdobeVFPrototype.abc.otf");
+  hb_face_t *face_ac = hb_test_open_font_file ("fonts/AdobeVFPrototype.ac.retaingids.otf");
+
+  hb_set_t *codepoints = hb_set_create ();
+  hb_face_t *face_abc_subset;
+  hb_set_add (codepoints, 'a');
+  hb_set_add (codepoints, 'c');
+  hb_subset_input_t *input = hb_subset_test_create_input (codepoints);
+  hb_subset_input_set_retain_gids (input, true);
+  face_abc_subset = hb_subset_test_create_subset (face_abc, input);
+  hb_set_destroy (codepoints);
+
+  hb_subset_test_check (face_ac, face_abc_subset, HB_TAG ('H','V','A','R'));
+
+  hb_face_destroy (face_abc_subset);
+  hb_face_destroy (face_abc);
+  hb_face_destroy (face_ac);
+}
+
+static void
+test_subset_identity_HVAR_noop (void)
 {
   hb_face_t *face_abc = hb_test_open_font_file("fonts/SourceSansVariable-Roman.abc.ttf");
 
@@ -49,7 +110,7 @@ test_subset_HVAR_noop (void)
 }
 
 static void
-test_subset_HVAR (void)
+test_subset_identity_HVAR (void)
 {
   hb_face_t *face_abc = hb_test_open_font_file ("fonts/SourceSansVariable-Roman.abc.ttf");
   hb_face_t *face_ac = hb_test_open_font_file ("fonts/SourceSansVariable-Roman.ac.ttf");
@@ -69,7 +130,7 @@ test_subset_HVAR (void)
 }
 
 static void
-test_subset_HVAR_retaingids (void)
+test_subset_identity_HVAR_retaingids (void)
 {
   hb_face_t *face_abc = hb_test_open_font_file ("fonts/SourceSansVariable-Roman.abc.ttf");
   hb_face_t *face_ac = hb_test_open_font_file ("fonts/SourceSansVariable-Roman.ac.retaingids.ttf");
@@ -96,9 +157,12 @@ main (int argc, char **argv)
 {
   hb_test_init (&argc, &argv);
 
-  hb_test_add (test_subset_HVAR_noop);
-  hb_test_add (test_subset_HVAR);
-  hb_test_add (test_subset_HVAR_retaingids);
+  hb_test_add (test_subset_map_HVAR_noop);
+  hb_test_add (test_subset_map_HVAR);
+  hb_test_add (test_subset_map_HVAR_retaingids);
+  hb_test_add (test_subset_identity_HVAR_noop);
+  hb_test_add (test_subset_identity_HVAR);
+  hb_test_add (test_subset_identity_HVAR_retaingids);
 
   return hb_test_run ();
 }